Polyester copolymer from terephthalic acid glycol and cycloaliphatic diol

ABSTRACT

Disclosed is a polyester copolymer obtained by reacting (A) a dicarboxylic acid component composed mainly of terephthalic acid or a derivative thereof with (B) a glycol component comprising (B-1) at least 0.5 mole % but less than 15 mole % of an aliphatic diol having 2 to 16 carbon atoms and (B-2) more than 85 mole % but not more than 99.5 mole % of 1,4-cyclohexanedimethanol having a trans form content of at least 80 mole %. This polyester copolymer has a high rate of crystallization and provides a shaped article having a high heat resistance.

DESCRIPTION

1. Technical Field

The present invention relates to a polyester copolymer having a highrate of crystallization and providing a shaped article having a highheat resistance.

2. Background Art

Polycyclohexylenedimethylene terephthalate obtained from terephthalicacid and 1,4-cyclohexanedimethanol has a high melting point, andtherefore, a molded article obtained from this polymer has a high heatresistance.

In this polymer, as the amount of the trans form of1,4-cyclohexanedimethanol is increased, the melting point becomes highand the heat resistance of a molded article obtained from this polymeris enhanced, but the glass transition temperature also becomes high andthe rate of crystallization is reduced. Accordingly, when it is desiredto obtain a molded article having a required heat resistance by usingpolycyclohexylenedimethylene terephthalate comprising a large proportionof the trans form of 1,4-cyclohexanedimethanol, a problem arises of anarrowing of the applicable range of shaping conditions, such as themold temperature.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a polyester copolymerhaving a high rate of crystallization and providing a shaped articlehaving a high heat resistance.

In accordance with the present invention, there is provided a polyestercopolymer obtained by reacting (A) a carboxylic acid component composedmainly of terephthalic acid or a derivative thereof with (B) a glycolcomponent comprising (B-1) at least 0.5 mole % but less than 15 mole %of an aliphatic diol having 2 to 16 carbon atoms and (B-2) more than 85mole % but not more than 99.5 mole % of 1,4-cyclohexanedimethanol havinga trans form content of at least 80 mole %.

BEST MODE FOR CARRYING OUT THE INVENTION

The dicarboxylic acid component (A) used in the present inventionpreferably comprises at least 90 mole % of terephthalic acid or aderivative thereof. As the derivative of terephthalic acid, there can bementioned dialkyl terephthalates having 1 to 10 carbon atoms in thealkyl group and diaryl terephthalates having 6 to 14 carbon atoms in thearyl group. As specific examples of the derivative of terephthalic acid,there can be mentioned dimethyl terephthalate, diethyl terephthalate,dipropyl terephthalate, dibutyl terephthalate and diphenylterephthalate.

As the other dicarboxylic acid used in an amount of up to 10 mole % incombination with terephthalic acid or the derivative thereof as thedicarboxylic acid component, there can be mentioned phthalic acid,isophthalic acid, adipic acid, sebacic acid,naphthalene-1,4-dicarboxylic acid and naphthalene-2,6-dicarboxylic acid.

The glycol component (B) used in the present invention comprises (B-1)at least 0.5 mole % but less than 15 mole % of an aliphatic diol having2 to 16 carbon atoms and (B-2) more than 85 mole % but not more than99.5 mole % of 1,4-cyclohexanedimethanol in which the trans form contentis at least 80 mole %.

As the aliphatic diol (B-1) having 2 to 16 carbon atoms, there can bementioned ethylene glycol, propylene glycol, tetramethylene glycol,hexamethylene glycol, neopentyl glycol, octamethylene glycol,butylethylpropanediol, diethylpropanediol and3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane.Ethylene glycol, propylene glycol, tetramethylene glycol andhexamethylene glycol are especially preferably used. These aliphaticdiols can be used alone or in the form of a mixture of two or morethereof. An aliphatic diol having more than 16 carbon atoms is notpreferred as the aliphatic diol because a polyester copolymer obtainedby using this aliphatic diol does not give a shaped article having asatisfactory heat resistance.

The amount of the aliphatic diol (B-1) having 2 to 16 carbon atoms, usedin the present invention, is at least 0.5 mole %, but less than 15 mole% based on the glycol component (B). A polyester copolymer in which theamount of the aliphatic diol (B-1) is smaller than 0.5 mole % based onthe component (B) is not preferable because the rate of crystallizationis low. Furthermore, a polyester copolymer in which the aliphatic glycol(B-1) occupies at least 15 mole % of the component (B) is not preferablebecause the melting point is low and little crystallization is caused.

In the 1,4-cyclohexanedimethanol used in the present invention, thecontent of the trans form must be at least 80 mole %. A shaped articleobtained from a polyester copolymer prepared by using1,4-cyclohexanedimethanol having a trans form content lower than 80 mole% does not have a satisfactory heat resistance.

The polyester copolymer of the present invention can be prepared bycarrying out an esterification reaction or an ester exchange reaction byusing terephthalic acid or a derivative of terephthalic acid such asdimethyl terephthalate, ethylene glycol or other aliphatic diol and1,4-cyclohexanedimethanol composed mainly of the trans form as thestarting materials, and subsequently, carrying out polycondensation.

Catalysts for use in the preparation of usual polyesters can be used forthe esterification or ester exchange reaction and the polycondensationreaction.

Additives such as a flame retardant, a fibrous reinforcer, a filler, anantioxidant, a heat stabilizer, a colorant and an ultraviolet absorbercan be added to the polyester copolymer of the present inventionaccording to need.

The present invention will now be described in detail with reference tothe following examples.

EXAMPLES 1 THROUGH 7 AND COMPARATIVE EXAMPLES 1 THROUGH 7

Terephthalic acid as the dicarboxylic acid and a glycol componentcomprising 1,4-cyclohexanedimethanol, ethylene glycol, 1,4-butanedioland 1,6-hexanediol at a ratio shown in Table 1 were subjected toesterification at 260° C. by adding 0.1% by weight, based on the weightof the final polymer, of tetrabutyl titanate as the esterificationcatalyst. Then antimony trioxide and phosphorous acid were added as thepolycondensation catalyst in amounts of 0.03% by weight and 0.04% byweight, respectively, based on the weight of the final polymer, andpolycondensation reaction was carried out at 285° to 320° C. under areduced pressure, whereby various polyester copolymers shown in Table 1were prepared. Each of the obtained polyester copolymers was recoveredin the form of a strand, cooled with water, and cut into a pellet by acutter.

The obtained polyester copolymer was decomposed with an aqueous solutionof hydrazine, and the glycol component was analyzed by the gaschromatography. The results are shown in Table 1.

The obtained polyester copolymer was dissolved inphenol/tetrachloroethane (1/1 weight ratio) and the intrinsic viscosityηsp/C was measured at a concentration of 0.5 g/dl. The results are shownin Table 1.

The obtained pellet was injection-molded into a molded article having athickness of 6.4 mm, a length of 127 mm, and a width of 12.6 mm, at acylinder temperature of 310° to 320° C. and a mold temperature of 70°C., by using a 1-ounce small-size injection molding machine. The heatdistortion temperature (HDT) was measured as the index of the rate ofcrystallization according to ASTM D-648.

The melting point was measured by using a differential scanningcalorimeter. From the results, it is understood that, when the ratiobetween 1,4-cyclohexanedimethanol and ethylene glycol in the polymer iswithin the specific range, and when the trans form content in1,4-cyclohexanedimethanol exceeds the specific level, a product having ahigh melting point and a large HDT value can be obtained and thiscopolymer has well-balanced properties.

Furthermore, from Table 1, it is seen that an aliphatic diol having 4 or6 carbon atoms is also effective.

                                      TABLE 1                                     __________________________________________________________________________           Transform                    HDT under                                        content                                                                             Composition of glycol                                                                           Melting                                                                            load of                                          in CHDM                                                                             component (mole %)                                                                              point                                                                              4.6 kg                                           (mole %)                                                                            CHDM EG BG HG ηsp/C                                                                         (°C.)                                                                       (°C.)                              __________________________________________________________________________    Example 1                                                                            90    99    1 -- -- 0.78                                                                              310  131                                       Example 2                                                                            90    95    5 -- -- 0.75                                                                              303  135                                       Example 3                                                                            90    90   10 -- -- 0.73                                                                              294  137                                       Example 4                                                                            95    90   10 -- -- 0.73                                                                              301  138                                       Example 5                                                                            83    90   10 -- -- 0.83                                                                              285  133                                       Example 6                                                                            90    95   -- 5  -- 0.73                                                                              301  137                                       Example 7                                                                            90    95   -- -- 5  0.71                                                                              298  136                                       Comparative                                                                          90    100  -- -- -- 0.76                                                                              312  105                                       Example 1                                                                     Comparative                                                                          90    75   25 -- -- 0.77                                                                              260  114                                       Example 2                                                                     Comparative                                                                          95    100  -- -- -- 0.75                                                                              314  107                                       Example 3                                                                     Comparative                                                                          83    100  -- -- -- 0.76                                                                              307  102                                       Example 4                                                                     Comparative                                                                          70    100  -- -- -- 0.75                                                                              286  108                                       Example 5                                                                     Comparative                                                                          70    100  -- -- -- 0.77                                                                              290   98                                       Example 6                                                                     Comparative                                                                          90    100  -- -- -- 0.76                                                                              312  105                                       Example 7                                                                     __________________________________________________________________________     Note                                                                          CHDM: 1,4cyclohexanedimethanol                                                EG: ethylene glycol                                                           BG: 1,4butanediol                                                             HG: 1,6hexanediol                                                        

INDUSTRIAL APPLICABILITY

The polyester copolymer of the present invention has a high rate ofcrystallization and a shaped article obtained from this copolymer has ahigh heat resistance. Accordingly, the range of utilization of thepolyester resin shaped article is wider.

We claim:
 1. A polyester copolymer obtained by reacting (A) adicarboxylic acid component consisting essentially of terephthalic acidor a derivative thereof with (B) a glycol component comprising (B-1) atleast 0.5 mole % but less than 15 mole % of an aliphatic diol having 2to 16 carbon atoms and (B-2) more than 85 mole % but not more than 99.5mole % of 1,4-cyclohexanedimethanol having a trans form content of atleast 80 mole %.
 2. A polyester copolymer as set forth in claim 1,wherein the derivative of terephthalic acid is a dialkyl terephthalatehaving an alkyl group having 1 to carbon atoms or a diaryl terephthalatehaving an aryl group having 6 to 14 carbon atoms.
 3. A polyestercopolymer as set forth in claim 1, wherein the aliphatic diol isethylene glycol.
 4. A polyester copolymer as set forth in claim 1,wherein the aliphatic diol is at least one member selected from thegroup consisting of propylene glycol, tetramethylene glycol andhexamethylene glycol.